Field of the Invention
The present invention relates to razors for shaving and, more particularly, to a system for electrically heating a series of razor blades within a blade cartridge.
Discussion of the Related Art
It is known that the cutting edge of a razor blade cuts hair more effectively when it is warm or hot. It is also common practice to place the razor blades under hot running water in order to heat the blades just prior to stroking the blades over the skin in order to cut the hairs. However, the heat cutting performance of the blades lasts only a short time during the beginning of the shaving stroke. Within seconds, the temperature of the skin surface, hairs and blade are quickly reduced due to exposure to the ambient air. Ideally, it is best to maintain the blades, including the cutting edges of the blades, heated to a warm temperature throughout the shaving process to achieve better performance and increased shaving comfort.
One particular prior art blade heating invention, disclosed in U.S. Pat. No. 6,817,101 B1 to Bohmer, provides a shaving system with a continuously heated blade cartridge throughout the shaving stroke. Heating the blades is attained by applying a measured amount of electric current to the blade cartridge by means of conductors connected to each side of the blade cartridge and extended in the form of contacts at the connection of the blade cartridge to a razor handle. Electric current is provided by a primary battery contained in a compartment in the razor handle. Current provided by the battery renders optimum heat generation in the blades of the cartridge and the degree of heat can be adjusted by means of resistors connected in series with the blades and the blade cartridge. A switch closes the circuit.
The present invention improves on the past heated blade systems by providing efficient heat distribution across each razor blade within a blade cartridge, as well as in between each razor blade. Specifically, the present invention uses two high resistance electrically conductive contact segments, such as Nichrome, connected to the back edges of the blades to deliver electric current flow through the blades as part of an electric circuit. The contact segments are connected to a power source (e.g., battery) by means of standard conductive wires such as copper or brass wire conductors. Nichrome (an alloy of nickel, chromium, and iron) is an example of a high electrical resistance conductor that can be used as the material for the contact segments. Due to the nature and material characteristics of the contact segments, as well as the junction of dissimilar metals between the contact segments, the standard wire conductors (e.g., copper or brass) and the blades, heat is generated in the contact segments causing them to become warm or hot when electric current flows through the circuit. This heat can be controlled by varying the diameter, shape, mass, and length of the contact segments for a given voltage. The spacing of the contact segments on the back edges of the blades helps to achieve more uniform heat distribution. Moreover, a radiator effect is created wherein heat produced by the contact segments, as a result of their high resistance, passes between the blades towards the cutting edges of the blades. A dual heat process is achieved by the combination of the heat produced by the electrically conductive blades as part of the electric circuit and the heat from the contact segments radiating between the blades. The improved means of heating the razor blades of the present invention provides increased efficiency of battery power usage, while also generating maximum heat with minimum voltage.